材料期刊网

In this work, we suggest a new and simple method named single gradient notched beam (SGNB) method for determining the fracture toughness of Ti(3)Si(Al)C(2) and Al(2)O(3) with four-point bending specimens. For the specimen with a gradient notch, a sharp natural crack will initiate and extends from the tip of the triangle under increasing load. Based on the straight through crack assumption or on the slice model, the stress intensity factor coefficient for this notched beam was derived. The fracture toughness can be calculated from the maximum load and the minimum of the stress intensity factor coefficient without knowing the crack length. To verify the feasibility and reliability of this suggested method, the SGNB method and two other conventional methods, e.g. the chevron notched beam (CNB) method and single edge notched beam (SENB) method, were performed to determine the fracture toughness of Ti(3)Si(Al)C(2) and Al(2)O(3). The measured fracture toughness values obtained from the SGNB method agreed well with those from conventional fracture toughness tests. (c) 2008 Elsevier Ltd. All rights reserved.